Lobeline is one of the lobelia alkaloids of Lobelia inflata (Indian tobacco, Emetic Weed, Asthma Weed) and is native to the eastern and central states of the USA and Canada. The plant contains about 0.3% alkaloids. The lobelia alkaloids are 2,6-disubstituted piperidine derivatives. Of the 20 or so lobelia alkaloids, lobeline is the main alkaloid. Lobeline is a respiratory stimulant when administered parenterally (3-10 mg) and was previously used as a respiratory analeptic to treat asthma, collapse and anaesthetic accidents. When taken orally it is rapidly broken down and therefore ineffective. As lobeline intensifies the effects of nicotine and thus induces retching and nausea, it has been developed clinically as a sustained-release agent for breaking the smoking habit (Drug News (25.3) 1996, 6).